It is now often mandatory to print not only characters and symbols, but also gradation image such as photograph of face of a person or a product on papers, cards, etc. such as visiting card, post card, advertising leaflets, personal history statement, personal record, identification card, etc. For example, visiting cards are now widely used as a kind of identification cards regardless of the type of profession, and it is now practiced to use a photograph of face of the bearer on a part of visiting card in order to increase the credibility of the visiting card.
As a method to add a photograph of face of the bearer on a visiting card, there is a method to attach a photograph of face, photographed or printed, on a mount of the visiting card, but this method is expensive and complicated. There is another method to provide a photograph of face by printing it when the visiting card is produced. Because the visiting cards are produced usually not in very large quantity, this requires expensive cost and long time until the visiting cards are completed, thus resulting much inconveniences.
Such problem is not limited to the visiting cards, but it occurs in the cases of paper mounts on various types of greeting cards, such as new year cards, letter of appreciation to the attendant in wedding ceremony, report on birth of a child, etc.
In general, to form characters, symbols and photographic images on plain paper at the same time, general-purpose photogravure or offset printing are widely used. However, expensive photoengraving and printing processes are required for such methods, and this results in the problem of cost in case of small-lot printing of several to several tens of copies although there is no such problem if printed in large quantity such as several thousands to several tens of thousand copies.
To solve the problem, various types of personal printers have been developed for personal use. However, it is difficult to form a gradation image such as photograph of face by heat fusion type thermal transfer. On the other hand, sublimation type thermal transfer can provide excellent gradation reproducibility and color reproducibility and can provide characters, symbols, etc. at the same time with a gradation image such as photograph of face, whereas special-purpose image receiving paper having resin layer in the surface is required.
FIG. 1 shows a transfer mechanism in such sublimation transfer method. In the figure, a transfer film 1 comprises a heat-resistant smooth layer 1a, a transfer base material 1b and dye layer 1c, which are laminated via primer for the better adhesion to the coating material. A film with easily adhesive treatment may be used. The heat-resistant smooth layer 1a consists of a mixture of polyvinyl butyral, polyisocyanate, and phosphoric acid ester. The transfer base material 1b consists of polyethylene terephthalate, polyimide, etc., and the dye layer 1c consists of sublimation dye of indoaniline type, pyrazolone type, azo type, etc. and a binder of polyvinyl acetal, cellulose type, etc.
The image receiving paper 2 comprises a receiving layer 2b and an image receiving paper base material 2a laminated via primer. The receiving layer 2b consists of saturated polyester, polyvinyl chloride, etc., and the base material 2a consists of synthetic paper, foamed polyester, foamed polypropylene, etc., and a rear surface layer consists of binder, lubricant, etc. A film of polyvinyl chloride resin may be used as the image receiving paper.
Around a platen roll 3, an image receiving paper 2 is wound. A transfer film 1 is closely overlapped on it. By applying a thermal head 4 on back side of the transfer film 1 and by heating, the sublimation dye is heated, moved and attached on the receiving layer 2b. In a sublimation transfer method, the dye is moved to the receiving layer according to the applied heat, and a recording with gradation can be provided according to the heat for each pixel dot.
In such sublimation transfer method, the quantity of the sublimation dye of the thermal transfer film is controlled according to image information and an image is recorded. Therefore, it is necessary to have special-purpose paper, which has a receiving layer where the sublimation dye can be attached.
In the thermal fusion type thermal transfer method, it is impossible to provide a gradation image such as photograph of face, while special-purpose image receiving paper is needed for the sublimation type thermal transfer method. For this reason, the following method is known: On plain paper surface, a dye receiving layer is partially formed by transfer, and a gradation image is formed on this receiving layer, while a non-gradation image such as characters, symbols, etc. are formed by heat fusion type thermal transfer on the other area.
However, dye is attached on the dye receiving layer in this method, and the dye image has some sort of durability such as anti-scratching property, while the image formed by heat fusion type thermal transfer method uses wax as a vehicle. Thus, the image lacks anti-scratching property, and only the wax image is deteriorated during handling. This leads to the deterioration of the image quality as a whole.
To solve such problem, there is another method to provide a transparent protective film on the wax image, whereas this means the addition of one more process and results in more complicated procedure.
With rapid internationalization of business activities and the increased popularity of overseas sightseeing travel, more and more passports are issued, and there arises a problem of passport falsification with such trend. On a passport, a photograph of face of the bearer is attached together with character information such as address, name, bar code, etc. to certify personal status of the bearer.
To attach a portrait photograph on a passport, a photograph of face separately photographed is usually attached on a mount of the passport by an adhesive. As described above, however, this method is troublesome and results in higher cost. Also, smoothness of the surface is lost due to the irregularities on the surface, and this is one of the causes of the delay in the issuance of the passports. In a passport with the attached photograph, there is a problem of falsification or alteration by re-attaching another photograph. This problem is not limited to passports, and there are similar problems with pocketbook, coupon tickets, notebook, etc., for which it is desirable to attach such photograph.
By the image forming method based on the sublimation transfer as described above, a photograph of face is provided as dye is attached into a base material of a card. This ensures surface smoothness, and the prevention of alteration and falsification. However, this is not totally effective in eliminating alteration or falsification of photograph and other information by removing protective layer using solvents, acids, bases, etc.
The present invention is to solve the above problems.
It is an object of the present invention to readily provide a gradation image such as a photograph of face and a non-gradation image such as characters on a mount of paper on a card such as visiting card.
It is another object of the invention to provide a dye image and a wax image with durability without increasing the number of processes.
It is still another object of the invention to provide a gradation image and a non-gradation image such as drawings and graphics by heat-sensitive sublimation transfer method without impairing smoothness, feeling and writability of plain paper.
It is yet still another object of the invention to readily provide a gradation image such as a photograph of face and a non-gradation image such as characters on a passport or other object.
It is still further object of the invention to promote the prevention of alteration and falsification.